Molecular script add-on will not run
I found the solution.

It turned out that I did not read PyroEvils instructions before installing the add-on.
I did have Microsoft Visual C++ 2013 Redistributable installed.
But in order to for the Molecular add-on 1.03 to run you need Microsoft Visual C++ 2015 Redistributable.
I got ITServicedesk to install the 2015-version and now the Molecular add-on runs as it should.

I made sure to make a donation to Jean-Francois.